 Continuous rotation servos are an easy way to add that robotic wheel your project needs. Unlike standard servos, varying the signal pulse width doesn't change which way a continuous servo points. Instead, it changes the speed and direction of its rotation. Using a one millisecond pulse width, this servo spins clockwise at full speed. As the pulse width gets closer to 1.5 milliseconds, it slows down. Then, as the pulse width extends to 2 milliseconds, the servo starts spinning counterclockwise faster and faster. You may find that even at exactly 1.5 milliseconds, the servo isn't completely stopped. It sort of drifts a little. Don't sweat it, just look for a hole in the body of the servo. This is for the adjustment potentiometer. While sending the servo precise 1.5 millisecond pulses, gently twist the pot until the servo is no longer drifting.